A Repeater For WWVB

For those living in the continental US who, for whatever reason, don’t have access to an NTP server or a GPS device, the next best way to make sure the correct time is known is with the WWVB radio signal. Transmitting out of Colorado, the 60-bit 1 Hz signal reaches all 48 states in the low-frequency band and is a great way to get a clock within a few hundred nanoseconds of the official time. But in high noise situations, particularly on the coasts or in populated areas these radio-based clocks might miss some of the updates. To keep that from happening [Mike] built a repeater for this radio signal.

The repeater works by offloading most of the radio components to an Arduino. The microcontroller listens to the WWVB signal and re-transmits it at a lower power to the immediate area, in this case no further than a few inches away or enough to synchronize a few wristwatches. But it has a much better antenna for listening to WWVB so this eliminates the (admittedly uncommon) problem of [Mike]’s watches not synchronizing at least once per day. WWVB broadcasts a PWM signal which is easy for an Arduino to duplicate, but this one needed help from a DRV8833 amplifier to generate a meaningfully strong radio signal.

Although there have been other similar projects oriented around the WWVB signal, [Mike]’s goal for this was to improve the range of these projects so it could sync more than a single timekeeping device at a time as well as using parts which are more readily available and which have a higher ease of use. We’d say he’s done a pretty good job here, and his build instructions cover almost everything even the most beginner breadboarders would need to know to duplicate it on their own.

2025 One Hertz Challenge: The Easy Way To Make A Nixie Tube Clock

Let’s say you want to build a Nixie clock. You could go out and find some tubes, source a good power supply design, start whipping up a PCB, and working on a custom enclosure. Or, you could skip all that, and just follow [Simon]’s example instead.

The trick to building a Nixie clock fast is quite simple — just get yourself a frequency counter that uses Nixie tubes for the display. [Simon] sourced a great example from American Machine and Foundry, also known as AMF, the company most commonly associated with America’s love of bowling.

The frequency counter does one thing, it counts the number of pulses in a second. Thus, if you squirt the right number of pulses to represent the time — say, 173118 pulses to represent 5:31 PM and 18 seconds — the frequency counter effectively becomes a clock. To achieve this, [Simon] just hooked an ESP32 up to the frequency counter and programmed it to get the current time from an NTP time server. It then spits out a certain number of pulses every second corresponding to the current time. The frequency counter displays the count… and there you have your Nixie clock!

It’s quick, dirty, and effective, and a sweet entry to our 2025 One Hertz Challenge. We’ve had some other great entries, too, like this nifty hexadecimal Unix clock, and even some non-horological projects, too!

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The 64-Degree Egg, And Other Delicious Variants

Many of us have boiled an egg at some point or another in our lives. The conventional technique is relatively straightforward—get the water boiling, drop the egg in, and leave it for a certain period of time based on the desired consistency. If you want the yolk soft, only leave it in for a few minutes, and if you want it hard, go longer.

Ultimately, though, this is a relatively crude system for controlling the consistency of the final product. If you instead study the makeup of the egg, and understand how it works, you can elicit far greater control over the texture and behavior of your egg with great culinary benefits.

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Buying Large LiFePO4 Batteries: How Cheap Is Too Cheap?

It’s a well-known factoid that batteries keep getting cheaper while capacity increases. That said, as with any market that is full of people who are hunting for that ‘great deal’, there are also many shady sellers who will happily sell you a product that could be very dangerous. Especially in the case of large LiFePO4 (LFP) batteries, considering the sheer amount of energy they can contain. Recently [Will Prowse] nabbed such a $125, 100 Ah battery off Amazon that carries no recognizable manufacturer or brand name.

Cheap and cheerful, and probably won't burn down the place. (Credit: Will Prowse, YouTube)
Cheap and cheerful, and probably won’t burn down the place. (Credit: Will Prowse, YouTube)

If this battery works well, it could be an amazing deal for off-grid and solar-powered applications. Running a battery of tests on the battery, [Will] found that the unit’s BMS featured no over-current protection, happily surging to 400 A, with only over-temperature protection keeping it from melting down during a discharge scenario. Interestingly, under-temperature charge protection also worked on the unit.

After a (safe) teardown of the battery the real discoveries began, with a row of missing cells, the other cells being re-sleeved and thus likely salvaged or rejects. Fascinatingly, another YouTuber did a similar test and found that their (even cheaper) unit was of a much lower capacity (88.9 Ah) than [Will]’s with 98 Ah and featured a completely different BMS to boot. Their unit did however feature something of a brand name, though it’s much more likely that these are all just generic LFP batteries that get re-branded by resellers.

What this means is that these LFP batteries may be cheap, but they come with cells that are likely to be of questionable quality, featuring a BMS that plays it fast and loose with safety. Although [Will] doesn’t outright say that you shouldn’t use these batteries, he does recommend that you install a fuse on it to provide some semblance of over-current protection. Keeping a fire extinguisher at hand might also be a good idea.

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VRML And The Dream Of Bringing 3D To The World Wide Web

You don’t have to be a Snow Crash or Tron fan to be familiar with the 3D craze that characterized the rise of the Internet and the World Wide Web in particular. From phrases like ‘surfing the information highway’ to sectioning websites as if to represent 3D real-life equivalents or sorting them by virtual streets like Geocities did, there has always been a strong push to make the Internet a more three-dimensional experience.

This is perhaps not so strange considering that we humans are ourselves 3D beings used to interacting in a 3D world. Surely we could make this fancy new ‘Internet’ technology do something more futuristic than connect us to text-based BBSes and serve HTML pages with heavily dithered images?

Enter VRML, the Virtual Reality Modelling Language, whose 3D worlds would surely herald the arrival of a new Internet era. Though neither VRML nor its successor X3D became a hit, they did leave their marks and are arguably the reason why we have technologies like WebGL today.

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A PC That Uses Hot Coffee As Coolant

Modern computers generate a great deal of heat when under load, thus we cool them with fans and sometimes even water cooling systems. [Doug MacDowell] figured that water was alright, but why not use coffee instead?

Someone tell us how [Doug] made this graph look like it’s right out of a 1970s college textbook.
The concept is simple enough — replace water in a PC’s cooling loop with fresh-brewed coffee. [Doug] fully integrated an entire PC build on to the side of a General Electric drip coffee maker. It’s an absolute mess of tubes and wires, but it’s both a PC and a functional coffee maker in one.

The coffee maker percolates coffee as per normal into the carafe, and from there, it’s then pumped through two radiators on top of the PC. From there, it circulates to the water block on top of the CPU, and then back to the carafe on the coffee maker where the cycle repeats. Doug notes the coffee is initially so hot (90 C) that the PC is at risk of crashing, but after 75 minutes circulating through the system, the coffee and CPU sit at an equilibrium temperature of 33 C.

You can’t really drink coffee from this machine. PC water cooling components are not food safe in any way, and [Doug] notes mold will become an issue over time. For short periods at least, though, it’s possible to sort-of-cool your computer with hot, fresh coffee if you really want to do that.

We’ve featured some great hacks of conventional coffee machines over the years, including this fantastic talk at Supercon 2023.

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330k volts

Sparks Fly: Building A 330 KV Supply From A PC PSU

If you’re hunting for a bench power supply, you’ll quickly notice options dry up above 48 V or so, and you definitely won’t find a 330 kV supply on the shelf at your local electronics shop. But with just a few parts, [Mircemk] has crafted a high-voltage source from a modified PC power supply that delivers electrifying results.

The sparks arcing over a foot of thin air are a dead giveaway, but let’s be clear: this project is not for beginners. High voltage — defined as around 1,000 V and up, with this project hitting 350 times that — carries risks of severe injury or death. Only tackle it if you fully understand the dangers and take precautions like proper insulation and never working alone.

This project showcases a Cockcroft-Walton voltage multiplier, a clever setup using diodes and capacitors to step up voltage. The capacitors charge and discharge in an alternating pattern, doubling the voltage after each diode pair. [Mircemk] uses 3 mm thick Plexiglas as an insulator, providing both structure and electrical isolation for the diode-capacitor cascade.

To achieve the 330,000 V output, [Mircemk] starts by modifying a standard PC ATX power supply, removing the Schottky diodes from the secondary winding’s output to produce a roughly 15 V square wave. This feeds into another transformer, boosting the voltage before it enters the Cockcroft-Walton multiplier. At first glance, the multiplier’s sides look identical, but their opposite polarities create a massive potential difference across the spark gap.

[Mircemk]’s benchtop exploration into high-voltage territory is a shocking success. If this project lights up your curiosity, dive into our other high-voltage adventures, like DIY Tesla coils or plasma speakers, for more electrifying inspiration.

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